Piston packing



Sept. 28 19265 W. H. CARMAN Pls'roN PACKING Filed July 5, 1924 2 Sheets-Sheetl 1 l l H llllllllll111111111111111111111,

Sept. 28 1926.

W. H. CARMAN PIsToN PgoKING i' Filed July 5 1924 2 Sheets-Sheet 2 iii WILLIAM H. CARMAN, 0F DETROT, MICHIGAN.

rIsToN PACKING.

Application led July 5,1924. Serial No. 724,338.

rlhis invention relates to piston-.s and has special reference to the packing or sealing of pistons relative to cylinder walls, for instance, the reciprocable pistons of pump or engine cylinders.

My invention, in its'broadest aspect,v1nvolves 'novel means in connection with the piston for adjusting a split piston ring in the wall of the piston so that the ring will be sealed at its split ends, prevented from circumf-erentially shifting relative to the piston, Vand during all strokes of the piston insure a better packing particlarly on the return stroke.

My invention is particularly characterized by a piston compression cap loosely articulated with the inner end of' the piston positioned to produce pressure on a piston ring during compression and power strokes'of vthe piston, so that the piston ring may have a double sealing action.

' My invention is further .characterizedY by a tubular piston body having one of its ends closed by -a-detachable cap screwed on the tubular piston body and locked thereon by means'which also serves to seal the split ends of a piston ring mounted in the tubular piston body and retained in place by the piston cap.

Other features of my invention will appear as the construction is hereinafter described and then claimed, and reference will now be had to the drawing, whereinvFigure l is a longitudinal sectional view of a portion of a cylinder and piston, the latter being in accordance with my invention;

Fig. 2 isa cross sectional view taken on the line IIII of Fig. 1; y

Fig. 3is a perspective view of a detached positioning Vblock ;l

Fig. 4 isa similar view of a 4detached pilot member;

Fig. 5 is a longitudinal sectional view of a portion of a cylinder and piston illustrating a modilication of my invention;

Fig. 6 is a similar view of ar further medilication of my invention;

Fig. 7 is a longitudinal sectional view of a portion'of the piston illustrating another modification of my invention;

view taken on Fig. 10 is a. side elevation of a portion of the piston showing a still further modi-j cation of my invention; n

Fig. 11 is a cross sectional view taken on the line XI-XI of Fig. 10, and Fig. 12 is a vertical .sectional view showing a locking device for a piston retaining ring. j

Reference will first be had to Figs. l to 4 inclusive showing a portion of a cylinder with' a portion of a piston 2 reciprocalole in the cylinder and said piston has its end reduced to provide a head 3 with an an nular shoulder 4: about said head, said shoulder cooperating with the head in providing two walls of a piston ring groove 5. The closed end of the head 3 is exteriorly screwthreaded, as at 6 and loosely mounted on said head is acap 7 having an annular liange or wall'8 which is interiorly screwthreaded and adapted to be .screwed ou the head 3, the screw threads of said head and said cap being such that there is a lost motion or loose connection between the head Y and cap permitting of slight longitudinal movement of the cap relative to the head 3.

Theedge of the cap lie-.nge or wall 8 pro`- vid-es the third wall of the groove 5 and in said groove is placed a conventional form of piston ring 9 having split ends 10, best shown in Fig. 2. l

One side of the piston head 3 is formed with an interior enlargement 11 provided with a socket 12 and slidable in said socket is a disk-like pilot member 13 having a concentric pilot pin 14 extending between the split ends lOvof the ring 9 to prevent circumferential creeping of the piston ring in the groove 5. pansion spring 15 pressing against the pilot member 13 to hold said member normally distended. v

At one side of the piston 2'the wall or shoulder 4 and the wall or flange 8 are provided with opposed segment shaped recesses 16 having walls described on arcs with radii the same as the recess or socket 12, so that Inl the socket 12 is a 'coiled exthe walls of the recesses 16 will be practically a continuation ot the walls of the socket 1Q. For instance, the cap 7 may be screwed on the head 3 and then said cap and head bored to form the recesses 1G and the socket 12.

Mounted in the recesses 16 and extending into the socket 12 is a two-part positioning block or button with the parts 17 thereotl substantially semi-cylindrical. The confronting edges of the bloclr parts 17 are recessed, as at 1S to provide an opening for the pilot pin 1-1 and the outer faces lof the block parts 17 are cut away so that said block parts may cooperate in forming a lchannel to receive the ends 10 ot the ring 9. Theifehannel is designated 19 and permitS ot ,one bloclrpaxrt overlying and the other block part underlying the split ends 10 ot' the piston VIt is now apparent that the split ends et' the ring are coupled by a block' which extends into the wall or flange 8 ot' the cap 7 and into the wall or shoulder itot the head 3, thus sea-ling the split ends ofthe piston ring relative 'to the piston. lt is also obvious that alter the positioning block is placed about the pilot pin 1l ot the pilot member 13 that said springl pressed pilot member ywill force'the positioning block outwardly against Xthe wall et the cylinder' 1 and being located between the head 3 and the cap 7 will l serve as loci;- ing means tor preventing the can 7 from unscrewing relative to the head 3 during the operation oi' the piston 2 in the cylinder 1.

Duringl compression and explosion 4strokes ot the piston and the cylinder 1 thil cap 7, by virtue of its loose connection 'with the head is forced towards the'head and the wall or flange S of the cap ,presses .the piston ring 9 against the wall or shoulder 4 ot the groove 5, at the same time pressingl the block parts 17 i'nt'o'closer relation so that the ends 10 ot' the piston ring 9 are positively sealed at the positioning block. Pressingl the piston ring 9 againstthe shoulder ilseals the cap 7 relative to the piston and there can be no leakage of gas around thel piston ring. in Fig. 5 the piston 2 has a head QQ open at both ends and the cap 7 closes the open outer end of said head. The cap 7 is formed with a flange or wall 21 ot greater depth than the flange or wall 8 so that the cap 7 will be positively guided by the head 2O when shitting thereon.

ln Fig. G a closed piston head 22 has an interinediate exterior screwthreaded portion 23 for a retaining ring which is used rin lieu of the cap 7, said retaining ring 4having a loose threaded connection and an annular guide flange 25 on the head 22. rPhe retaining ring 24 will yield when subjected to pressure and will pack the piston ring 9 in a manner similar to the caps 7.

lV-hen the piston is not within the cylinder 1 the positioning blocl; engaging the split ends 10 of the ring 9 maintains the parts assembled against accidental loss.

Reference will now be had to a :ter: modifications ot my invention, first, that disclosed in Fig. 7. rlfhe reduced end 26 of the piston 27 is provided with a conventional Jrorm of piston ring QS having split bias ends, devoid ot any positioning or coupling member, and pressure may be brought to bear von the piston ring 28 by a retaining ring 29 loosely screwed on the reduced end 2G `ot the piston and loosely locked thereon by a cotter pin BO anchored relative to a recess wall 31 ot the piston. This is an instance where means loose on the reduced end ot the piston may bring pressure to bear upon packing means on the piston.

Practically the same retaining ring 29 is utilized in the construction sliownin Figs. S and 9, ybut in this instance the outer end of the piston 27 has` a chamber or recess in*- creasing the volumetric compression space between the end ol the piston and the cylinder, but, in lieu et the piston ring 2S, I provide special superposed piston rings `33 and 3-1 which mayliave pressure brought to bear thereon by thel retaining ring 29. The rings 33 and 3-1 are identical in construction, each having an outer cylindrical wall and 'an inner elliptical wall which causes each ring" tn have relatively thicl; and thin portions. the thin portions being dian'ietrically opposed and at a right angle to the diametrically opposed thicl; portions. 1n assembling the rings the diametrically opposed thicli portions ,o't' one ring are placed at a right angle to the diametrically opposed thick portions of the adjacent ring,`as brought out in Fig. l9, and to atv all times maintain this relation and prevent one ring Y trom circumterentially creeping relative to its adjacent ring, a resilient coupling member 35 is employed. This coupling member has an angular end engaging in a notch 3G in the thick wall ot one ring and an angular end engaging in a similar notch in the thick wall ot the other ring. The joined rings may bodily shit't circumerentially of the piston, but not one independentet the other. rl'he rings may he made in various ways so that the natural shape of each ring, outside of a piston. will be substantially elliptical er oval necessitating compression or contraction of portions of the ring towards cylindrical 'lorm in order that the ring, either oit or on a piston, may be placed in a cylinder. Such a ring will have an inherent tendency to hug the walls of the cylinder in which the piston recipreeates, thus sealing the piston relative to the cylinder wall.

Reference will now be had to Fig-. 10 and 11 again showing the piston 27 provided with the retaining ring Q9 and this retaining ring is adapted ,to bring pressure to hear on lof) llf)

l it) one or more piston rings 37 having split ends with a pilot pin or positioning block 3S therebetween, saidl pilot pin or positioning block being carried bya resilient segment vshaped member 39. located against thereduced end ot the piston 27. 'Ihe expansive torce ot this member will hold the pilot pin against the cylinder wall and by reason of its resiliency frictiona'lly engage the piston and prevent circumferential Ycreeping of the piston ring. This resilient member is used in lieu of a positioning block and pilot member and is an example of other forms of resilient members that could be used for the same purpose.

For some types of pistons having comparatively thin walls, it may be impossible to conveniently use the cot-ter pin or a positioning member for preventing rotation of the retaining ring 29. I may therefore Y provide a retaining ring with opposed recesses 40 for the angular ends 41 of a locking member 42 wh-ich may extend transversely ot the piston and be spot welded or otherwise connected thereto, as at 48. The looking member 42 will prevent accidental rotation of the retaining ring 29, and when it is necessary to remove said ring, the spot welding may be ground to release the locking member 42, which may again be secured to the piston, by spot welding, after the retaining ring 29 has been adjusted. This has been shown in Fig. 12, and .I also show a small positioning member 44 between the confronting edges of the piston rings 33 and 34, said piston rings being notched to receive the positioning member 44, preferably in the form of a headed pin, adapted to prevent circumferential creeping of one ring relative to the other.

Again referring to that type of piston having a positioning member, I desire to direct attention tothe fact that the cap 7 constitutes means, movable on the endv of the piston, for bringing pressure to bear on the edge of the piston ring 9 so that the opposite edge of the "iston ring will be packed against the piston. It is in this connection that the piston ring 9 represents one or more packing rings or members about the piston and if pressure is brought to bear upon one packing member others may be crowded so as to seal t-he'piston relative to the cylinder. Furthermore, I desire to point out that the cushioning block, being made ot' two parts is applicable to piston rings of different widths for the reason that the parts of the positioning block may be brought closer together or separated farther apart. Another advantage is gained in "3 making `the block ot two channel parts,

namely that of preventing rotation of the block when the splitends of the piston ring project into the block. It is by virtue of such split ends that the parts are held assembled when the piston is outsiderot the cylinder,

scription, and while in the drawings there are illustrated the'preferred embodiments of my invention, it is to be understood that the structural elements are susceptible to such variations and modifications as :tall Within the scope of the appended claims.

lVhat I claim is l. Ina piston, adjacent rings, each ring having opposed thick walls and opposed relative thin walls, .one ot said rings being positionedv so that its relatively thin walls are adjacent the thick walls of the other ring.

2. In a piston, adjacent rings, each having an outer out-o'f-round wall with the major axis of one ring approximately parallel to the, minor axis of the other ring.

3. The combination of a piston, packing means about said piston and a cap in loose screw-threaded engagement with said piston against said packing means and adapted to exert a pressure on said packing means during reciprocation of said piston.

4. A piston packing comprising rings c0- operating in forming a substantially outer cylindrical wall, said rings having outer walls out-of-round with said rings arranged so that outer wall portions of one ring are offset relative to outer wall portions of the other'l ring. 5. The combination with a piston having a groove with the split piston ring in said groove, of a two-part positioning block at the split ends of said piston ring, and a movable cap on said piston held against rotation kby said block and adapted to exert pressure on said block and said piston ring during reeiprocation of said piston.

6. Therombination set forth inrclaim 5,

and a pilot member mounted in said piston and extending into said block. 7. The combination with a piston and a piston ring mounted therein, of a cap loosely screwed on said piston and during reciprocation thereof adapted to exert pressure on said piston ring to crowd it on said piston, and ayieldable block set in said piston and a portion ot said cap and adapted `to prevent rotation of said cap relative to said piston.

8. The combination called for in claim 7, wherein said block is composed of two parts one of which extends into said cap and the other into said piston, said block parts having n channel to receive said piston ring.

9. The combination of a piston a. movable cap on said piston, a fewo-part block having a part n said cap and a part in said piston, and a split ring held on said piston by said cap und having; its split ends eziendnlg between the parts of said block.

10. The Combination with a Cylinder, of

w continuons uninterrupted piston rings norlnally out of round and adapted ro be eo1npressed to enter Said cylnder, said rings haring inner Walls of oval confgm'nion.

11. The eon'lbination Called 'for in claim l0, said rings positioned with the nxzxjor axes thereof at an angle relatve to euch other.

In tesnnonj: whereof I affix my Sgnatrre.

VILLLXM H. CAUUQT. 

